During the manufacture of spray-dried milk products, the lactose may crystallize (process during which α-lactose picks up a molecule of water) whereas the hygroscopicity and caking properties decrease. A new modified method was used to determine of the hygroscopicity of whey and milk powders according to the conditions of lactose crystallization. Hygroscopicity was determined using a desiccator with a saturated solution of Nal (39% relative humidity) in the place of NH_4C1 (80% relative humidity) at20°C, in relation to time. Moreover, this new method was performed in static state and not in dynamic conditions (as in reality). Results concerning hygroscopicity are also presented for various milk, whey and lactose powders, with degrees of crystallinity of a-lactose monohydrate ranging from 0 to 100%.
展开▼
